1. Field of the Invention
This invention relates to semipermeable membranes. In one aspect, the invention relates to semipermeable membranes prepared from polymers containing pendent sulfone groups while in another aspect, the invention relates to the use of these membranes to separate various gaseous mixtures, such as carbon dioxide and methane, into enriched fractions of their constituent parts.
2. Description of the Prior Art
The art is replete with teachings describing various semipermeable membranes, their preparation and use. Robb, U.S. Pat. No. 3,350,844, teaches the enrichment of gases by permeation through a thin permeable film or membrane prepared from a polyarylene oxide film. Ward and Salemme, U.S. Pat. No. 3,780,496, teach the use of sulfonated polyxylylene oxide membranes to separate helium, hydrogen and oxygen from gas mixtures.
While the membranes of the above teachings and others all display some level of utility, there exists a continuing search for new membranes and new applications for both new and known membranes. One application where the use of membrane technology may prove beneficial is in the separation of gaseous carbon dioxide-methane mixtures into enriched fractions of their constituent parts. Natural gas is generally found in combination with carbon dioxide. Removal of the carbon dioxide from the natural gas is desirable because it results in both a product (purified natural gas) of greater commercial worth and it provides purified carbon dioxide useful for other applications, such as enhanced oil recovery. Conventional separation processes generally employ cryogenic methods which are relatively energy intensive.